BRISBANE, Australia (AFP) - Tennis' world No. 2 Garbine Muguruza suffered a fitness scare ahead of this month's Australian Open when she was forced to retire from the Brisbane International on Tuesday with severe cramping.
The Wimbledon champion was ahead 2-1 in the deciding set against Serbia's Aleksandra Krunic in the second round of the warm-up tournament for the season's first Grand Slam event when she collapsed to the ground following a serve.
The Spanish top seed was unable to continue and handed the match to Krunic 5-7, 7-6 (7-3), 2-1.
"I felt in trouble in the second set when I was 2-0 up," Muguruza said.
"I started to feel my calves were cramping."
At the same time, former world No. 1 Andy Murray has withdrawn from the tournament in a major setback to his Melbourne Park preparations.
He suffered a right hip injury in 2017 and has not played on the ATP Tour since losing a tough five-setter to American Sam Querrey in the quarter-finals at Wimbledon.
He said on Sunday that he felt in great shape and that he was confident he would play in Brisbane. But the 30-year-old Scot issued a statement on Tuesday announcing his withdrawal from the tournament, and did not say whether he would be able to play the year's first Grand Slam.
Meanwhile, Muguruza had won a tight first set and appeared heading for a straight-sets win over Krunic when she opened up a 5-2 lead in the second.
However, she began to struggle in the 30 deg C heat and oppressive humidity as Krunic fought back to win the second set on a tie-break.
Muguruza received treatment from the physio on court before the start of the decider and broke Krunic only to collapse while serving to consolidate the service break.
"I continued to think that with the match they might go away, and then they were increasing, increasing. And then I had a lot of my body cramping," she said.
The loss ends any hope Muguruza had of leapfrogging Simona Halep and becoming world No. 1 before the seedings are decided for Australian Open, which begins on Jan 15.
But Muguruza was not too downhearted by having to withdraw.
"I'm pleased because we were playing very good points and, you know, good rallies," she said.
"I felt it was a good level, a good match, but I wanted to finish to see, to evaluate how the match was, but I'm happy with the way I was playing."
Krunic will now play either Sorana Cirstea or Anastasija Sevastova in the quarter-finals.
Last year's runner-up Alize Cornet eased into the final eight with a straight-sets win over Croatia's Mirjana Lucic-Baroni.
Cornet, who won her first-round match when fourth seed Caroline Garcia retired injured, was too consistent for Lucic-Baroni, winning 6-1, 7-5.
In the men's draw, 21-year-old South Korean Chung Hyeon stunned fifth seed Gilles Muller from Luxembourg 6-3, 7-6 (7-1), while US qualifier Michael Mmoh upset Argentinian Federico Delbonis 6-3, 6-4.
Murray said he would stay in Brisbane as he "works towards returning to the tennis circuit".
"I'm very disappointed to be withdrawing from the Brisbane International," he added.
"I came here with every intention of making a strong start to the year, but sadly my team and I don't feel that I'm where I need to be just yet to compete at the highest level."
Murray joins top seed and world No. 1 Rafael Nadal, who pulled out of the tournament late last week, on the sidelines.